Evolution of Product Lifespan and Implications for Environmental Assessment and Management: A Case Study of Personal Computers in Higher Education

School of Human Evolution and Social Change, Arizona State University, PO Box 872402, Tempe, Arizona 85287-2402, USA.
Environmental Science and Technology (Impact Factor: 5.33). 08/2009; 43(13):5106-12. DOI: 10.1021/es803568p
Source: PubMed


Product lifespan is a fundamental variable in understanding the environmental impacts associated with the life cycle of products. Existing life cycle and materials flow studies of products, almost without exception, consider lifespan to be constant over time. To determine the validity of this assumption, this study provides an empirical documentation of the long-term evolution of personal computer lifespan, using a major U.S. university as a case study. Results indicate that over the period 1985-2000, computer lifespan (purchase to "disposal") decreased steadily from a mean of 10.7 years in 1985 to 5.5 years in 2000. The distribution of lifespan also evolved, becoming narrower over time. Overall, however, lifespan distribution was broader than normally considered in life cycle assessments or materials flow forecasts of electronic waste management for policy. We argue that these results suggest that at least for computers, the assumption of constant lifespan is problematic and that it is important to work toward understanding the dynamics of use patterns. We modify an age-structured model of population dynamics from biology as a modeling approach to describe product life cycles. Lastly, the purchase share and generation of obsolete computers from the higher education sector is estimated using different scenarios for the dynamics of product lifespan.

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    • "Obsolete computer quantities are defined as an expected value of the sales of computers with the probability this quantity of computers to be considered as obsolete. Yet, as there is a different lifespan distribution in each of the regions of the world, each region is tested based on fitting indices with the widely known continuous distributions that have been utilized, up to now, to model this specific type of data (Normal, Weibull, Lognormal, Logistic, Cauchy, and Exponential) (Babbitt et al., 2009). The obsolete computer quantities are estimated for the same time horizon as the historical computer sales data. "
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    ABSTRACT: Technology changes rapidly over years providing continuously more options for computer alternatives and making life easier for economic, intra-relation or any other transactions. However, the introduction of new technology “pushes” old Information and Communication Technology (ICT) products to non-use. E-waste is defined as the quantities of ICT products which are not in use and is bivariate function of the sold quantities, and the probability that specific computers quantity will be regarded as obsolete. In this paper, an e-waste generation model is presented, which is applied to the following regions: Western and Eastern Europe, Asia/Pacific, Japan/Australia/New Zealand, North and South America. Furthermore, cumulative computer sales were retrieved for selected countries of the regions so as to compute obsolete computer quantities. In order to provide robust results for the forecasted quantities, a selection of forecasting models, namely (i) Bass, (ii) Gompertz, (iii) Logistic, (iv) Trend model, (v) Level model, (vi) AutoRegressive Moving Average (ARMA), and (vii) Exponential Smoothing were applied, depicting for each country that model which would provide better results in terms of minimum error indices (Mean Absolute Error and Mean Square Error) for the in-sample estimation. As new technology does not diffuse in all the regions of the world with the same speed due to different socio-economic factors, the lifespan distribution, which provides the probability of a certain quantity of computers to be considered as obsolete, is not adequately modeled in the literature. The time horizon for the forecasted quantities is 2014–2030, while the results show a very sharp increase in the USA and United Kingdom, due to the fact of decreasing computer lifespan and increasing sales.
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    • "Cathode ray tubes (CRTs) have been widely used as a video display component of both televisions and computers, representing a significant and challenging fraction of the end-of-life electronics waste stream (Lee and Hsi, 2002; Lee et al., 2004; Li and Wen, 2006; Poon, 2008). Because of their volume and toxicity, obsolete CRTs pose a major concern in Waste Electrical and Electronic Equipment (WEEE) recycling (Babbitt et al., 2009; Nnorom et al., 2011). "
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    Full-text · Article · Aug 2015
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    • "The rapid technological change, especially in electronic market leads consumers to purchase more products while creating consequences such as decreasing products usage time (Babbitt et al., 2009), progression of products obsolescence and accelerating Electronic Waste (e-waste) generation. E-waste is the fastest growing waste stream in the US and many other countries. "
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